Defaulted Types

When inserting rows, some columns have database defaults (auto-increment IDs, timestamps, etc.). The Defaulted type lets you explicitly choose: provide a value, or use the database default.

The Defaulted Type

Typr generates a Defaulted<T> type in your project:

Defaulted

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2

JavaKotlinScala

Full file

/** This signals a value where if you don't provide it, postgres will generate it for you */
public sealed interface Defaulted<T> permits Defaulted.Provided, Defaulted.UseDefault {
  record Provided<T>(T value) implements Defaulted<T> {
    public Provided<T> withValue(T value) {
      return new Provided<>(value);
    }

    @Override
    public <U> U fold(
        java.util.function.Supplier<U> onDefault, java.util.function.Function<T, U> onProvided) {
      return onProvided.apply(value);
    }

    @Override
    public T getOrElse(java.util.function.Supplier<T> onDefault) {
      return value;
    }

    @Override
    public void visit(java.lang.Runnable onDefault, java.util.function.Consumer<T> onProvided) {
      onProvided.accept(value);
    }
  }

  record UseDefault<T>() implements Defaulted<T> {
    @Override
    public <U> U fold(
        java.util.function.Supplier<U> onDefault, java.util.function.Function<T, U> onProvided) {
      return onDefault.get();
    }

    @Override
    public T getOrElse(java.util.function.Supplier<T> onDefault) {
      return onDefault.get();
    }

    @Override
    public void visit(java.lang.Runnable onDefault, java.util.function.Consumer<T> onProvided) {
      onDefault.run();
    }
  }

• Provided(value) - Use this specific value
• UseDefault - Let the database generate the value

Unsaved Row Types

For tables with default columns, Typr generates an "Unsaved" row type:

CompanyRowUnsaved

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2

JavaKotlinScala

Full file

/** This class corresponds to a row in table `showcase.company` which has not been persisted yet */
public record CompanyRowUnsaved(
    CompanyId id,
    String name,
    Optional<Integer> foundedYear,
    /** Default: true */
    Defaulted<Optional<Boolean>> active,
    /** Default: CURRENT_TIMESTAMP */
    Defaulted<Optional<LocalDateTime>> createdAt) {
  public CompanyRowUnsaved(CompanyId id, String name) {
    this(id, name, Optional.empty(), new UseDefault<>(), new UseDefault<>());
  }

Notice how active and createdAt are wrapped in Defaulted—they have database defaults. The id, name, and foundedYear columns don't have defaults, so they're required.

Using Defaulted

Insert with defaults:

// Java - use database defaults
var unsaved = new CompanyRowUnsaved(
    new CompanyId(1),
    "Acme Corp"
);
CompanyRow saved = repo.insert(unsaved, conn);
// saved.active() will be true (the database default)
// saved.createdAt() will be the current timestamp

// Kotlin - use database defaults
val unsaved = CompanyRowUnsaved(
    id = CompanyId(1),
    name = "Acme Corp"
)
val saved = repo.insert(unsaved, conn)

Override a default:

// Java - provide a specific value
var unsaved = new CompanyRowUnsaved(
    new CompanyId(1),
    "Acme Corp",
    Optional.empty(),
    new Defaulted.Provided<>(Optional.of(false)),  // Override active
    new Defaulted.UseDefault<>()                    // Use default for createdAt
);

Repository Methods

Repositories accept both regular rows and unsaved rows:

CompanyRepo

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2

JavaKotlinScala

Full file

  CompanyRow insert(CompanyRow unsaved, Connection c);

  CompanyRow insert(CompanyRowUnsaved unsaved, Connection c);

  Long insertStreaming(Iterator<CompanyRow> unsaved, Integer batchSize, Connection c);

  /** NOTE: this functionality requires PostgreSQL 16 or later! */
  Long insertUnsavedStreaming(Iterator<CompanyRowUnsaved> unsaved, Integer batchSize, Connection c);